Studies outlined in this application propose to examine the relationship between the brain's ability to Inhibit incoming irrelevant sensory input (sensory gating and habituation) and (the absence of) phase resetting of the ongoing EEG. The relationship between the ability of the brain to respond to stimulus change (dishabituation) and phase resetting of the EEG will also be studied. Our first aim is to provide data supporting the hypothesis that phase resetting of the EEG (phase synchronization) plays an important role in determining the brain's response to novel stimuli. We also plan to show that the failure to phase reset the EEG plays a significant role in allowing the organism to stop responding (or inhibit the response) to repetitive irrelevant stimuli. Finally, we will demonstrate that both processes are deficient in schizophrenia patients. Utilizing a fuzzy logic technique and a single trial analysis method (both developed by this group) evoked potential data containing the P50 mid-latency auditory component will be compared between a group of schizophrenia patients and a group of age and sex matched normal controls. Data will be collected at the West Haven Veterans Hospital/Yale University and will be blindly analyzed in Dr. Jansen's laboratory at the Department of Computers and Electrical Engineering of the University of Houston. Data provided through this study will shed more light on the physiological mechanisms mediating the protective fundamental function of habituation. Elucidation of abnormalities of this function in schizophrenia patients will increase our understanding of this complex disorder and may contribute to developing more effective diagnostic instruments and therapeutic and rehabilitative interventions.